1. Field of the Invention
The present invention relates to an apparatus for measuring radioactivity of radioactive particles without loss of the radioactive particles, and more particularly, to an apparatus for measuring radioactivity without loss of radioactive particles, which can accurately measure a radioactivity of radioactive particles included in a radioactive sample collected from air including the radioactive particles when measuring the radioactivity of the radioactive sample.
2. Description of the Related Art
In nuclear power plants, there are radioactive materials that are generated in nuclear fission in a nuclear reactor and in processing a nuclear fuel and radioactive waste. It is very important to accurately measure a radioactivity included in air in order for radioactive materials not to harm the health of the general public and operators of nuclear power plants.
Representative radioactive materials in air are classified into a particulate radioactivity, iodine, and a rare gas, and detected. In conventional nuclear power plants, generally, since a sufficient space for installing a radioactivity detector is not secured near pipes and ducts and it is unable to install a radioactivity measuring apparatus in an area in which pollution of electronic equipment is expected, a sampler for collecting a radioactive sample is installed in each of the pipes and ducts, and a radioactive sample collected by the sampler is transported through a transport pipe that extends by a considerable length. A radioactive detector is installed at an end portion of the transport pipe, and measures a radioactivity of the radioactive sample received through the transport pipe.
However, since particulate radioactive materials included in the radioactive sample have a size and a weight, the particulate radioactive materials are deposited on a bottom of the transport pipe due to gravity, and the particulate radioactive materials are lost due to the roughness of an inner wall, a gap of a joint, or an isolation valve of the transport pipe. For this reason, when the transport pipe is considerably long, a value measured by the radioactivity detector is very inaccurate.
Moreover, since a position at which the sampler is installed is limited to a position which is checked through a flow analysis of a pipe or duct as having a small speed deviation and relatively uniformly distributed radioactive samples, the transport pipe connecting the sampler to the radioactivity detector becomes longer, and particulate radioactive materials are accordingly greatly lost.
It is required to correct an inaccuracy of a measurement value in consideration of the loss of particulate radioactive materials. However, considering all accurate basis data of loss factors generated in construction, such as the specifications of used materials and the position of a joint, is very difficult, and moreover, there is no method that quantitatively, accurately measures a loss rate. There remains a limitation in that an inaccurate measurement value is inevitably used as-is.